Data centers are often used by providers to deliver computing services to users. A data center, such as a server farm, typically contains hundreds or thousands of processing devices. Within the data centers the processing devices are arranged in clusters. Each cluster is configured to perform a distributed task in a parallel fashion. Naturally, the data centers consume a large amount of power, and the amount of power consumed by data centers is directly related to the expense of operation and efficiency.
Moreover, data centers contain many different types of electrical devices and elements that may be expensive to replace. Therefore, protection circuits and devices are used to protect the devices and elements of data centers. One such protection circuit is a hot swap controller. A hot swap controller facilitates addition of electrical devices to a system without removing power from other electrical devices in the system, while providing electrical protection for the electrical devices. An example use of a hot swap controller is in a server rack, where server devices may be added by inserting the server devices while other server devices in the server rack and on the same power bus remain powered. When the server device is coupled to the server rack, and thus to the power bus, the hot swap controller monitors the supply voltage and other conditions, such as current, and can control the power up of the server device so as to avoid transients, such as excessive inrush currents. Once the server device reaches a powered state that meets a threshold, the hot swap power controller generates a “power good” signal to indicate to the server processor (or other system components) that the server device is now operable.
To monitor the protected circuit, the hot swap controller utilizes a small resistor as a current sense resistor. However, the hot swap circuit does not provide full protection as it may fail to provide short circuit protection. Thus, additional electrical protection is required for the tray housing the devices, such as fuses. These fuses have internal resistances, this is typically on the order of magnitude of the sense resistor, and are connected in series with the resistive load.